API for requesting information about containers

[not-first]

Description

Diun should have a API (that perhaps could be optionally enabled) that has simple functionality for fetching the status of containers.

For example, there could be an endpoint to fetch all outdated containers. Or, an endpoint where you can feed in a container name and receive if it is up to date.

This would allow easy integration into other services and systems, to display real time data about outdated containers which would serve as an alternative to notifications.